The braod objectives of the research supported by this grant are the elucidation and characterization of the molecular interactions responsible for RNA-protein complex formation and their inhibition by the triphenylmethane dye aurin-tricarboxylic acid (ATA). We have adopted a restricted focus by considering only certain proteins that are involved in some aspects of protein biosynthesis, viz., ribosomal protein Sl, Initiation Factors 1 and 3, Elongation Factors Tu and Ts, and Host Factor I. We are also interested in the mechanism of action of ATA, a potent inhibitor of protein nucleic acid complex formation.